15 replies to this topic

[Hegnirst]

im getting 1300 metro engine in a couple a couple of days, first, is a 1300 metro engine a 1275?, if it is a 1275, can it be bored out?

would it be easy for a specialist to do? or is it costly to bore? what would it be?

and would my diff from my 998 fit with the metro engine easily? as my diff is bigger

thank you in advance

[L400RAS]

first, is a 1300 metro engine a 1275?

Yes

if it is a 1275, can it be bored out?

Yes

would it be easy for a specialist to do?

Yes

or is it costly to bore?

Shop around, and get friendly with an engine builder

what would it be?

As in CCs? depends on how much you bore it. +20, +40, +60, +80..
You can achieve up to around 1430 cc, with different pistons / crank. (Larger bores require offset boring)

and would my diff from my 998 fit with the metro engine easily? as my diff is bigger

Not sure, but my question is, will it cope if you go for a big engine?

Edited by L400RAS, 29 December 2010 - 08:27 AM.

[Hegnirst]

thankyou for the reply

thats cleared a lot up aha!
what can it be bored out too without being unreliable and where i have to start changing pistons crankshafts etc? offset boring? what is it and is it only necessary after a certain amount of bore out?

how would i know if it would cope?

thanks again

Edited by Hegnirst, 29 December 2010 - 08:31 AM.

[L400RAS]

Hi mate,

As soon as you rebore, you will be looking for new pistons, so there's a cost. A simple 1293 / 1310 should be straight bored, using the same crank (possible re-grind may be required on yours - more cost). 1310 should still be very reliable. 1380s can still be reliable, but like everything, will cost, and you will need to look after it.


Offset boring - essentially on the larger bores, the wall between 2 & 3 gets VERY thin if it is straight bored. Offsetting - ie moving the centre of the bore away will allow for larger bores. The head gasket should be used to centralise the bore i think. Professional job.

Edited by L400RAS, 29 December 2010 - 08:37 AM.

[Paul Wiginton]

I believe it's a myth about tuned engines becoming unreliable. Aslong as you use quality matched components and build it perfectly it will be as reliable as an 850.
My 1380 firebreathing drag race engine is as reliable as any other engine on this forum because I build it right. If you do too you'll be ok

Paul

Edited by Paul Wiginton, 29 December 2010 - 09:02 AM.

[Cooperman]

I believe it's a myth about tuned engines becoming unreliable. Aslong as you use quality matched components and build it perfectly it will be as reliable as an 850.
My 1380 firebreathing drag race engine is as reliable as any other engine on this forum because I build it right. If you do too you'll be ok

Paul

Absolutely right there Paul. My 1310 cc 'S' engine has been used in competition. All the parts are the very best quality - Karl Schmidt pistons, etc., and it has proved very reliable.
I always think a bore to 1330 (+0.060") is good for a road car with 21253 pistons as that won't require offset boring and the pistons are adequate and not too expensive at c. £140 for a set. It can then still be bored further if necessary at a later date.

[wzd345]

Start at the beginning.

How much money do you have, what are your own skills or are you getting somebody else to do the work and what do want from the project??

Without a budget and a plan of action, its a disaster.

[Cooperman]

I always think a bore to 1330 (+0.060") is good for a road car with 21253 pistons as that won't require offset boring and the pistons are adequate and not too expensive at c. £140 for a set. It can then still be bored further if necessary at a later date.

If you bore a large block out +60thou WITHOUT offsetting the bore, it's scrap after that (yes ok it can be linered back).

BUT if you offset you can go bigger to 1360. 1380 & 1399.

I think you'll find that if you offset a 1330 cc bored block by 0.020" each way, it'll go bigger. I would always sleeve back to 1275 as they are not going to make any more A-series blocks and in the future the scrappage of offset and oversize bored blocks which won't go any bigger will cause problems.

[Cooperman]

I always think a bore to 1330 (+0.060") is good for a road car with 21253 pistons as that won't require offset boring and the pistons are adequate and not too expensive at c. £140 for a set. It can then still be bored further if necessary at a later date.

If you bore a large block out +60thou WITHOUT offsetting the bore, it's scrap after that (yes ok it can be linered back).

BUT if you offset you can go bigger to 1360. 1380 & 1399.

I think you'll find that if you offset a 1330 cc bored block by 0.020" each way, it'll go bigger. I would always sleeve back to 1275 as they are not going to make any more A-series blocks and in the future the scrappage of offset and oversize bored blocks which won't go any bigger will cause problems.

Sounds like a bit of a contradiction to me

In what way? I would always sleeve back to 1275 on any of my own cars. My 1964 'S' is now at 1310 cc. It will take one more bore to 1330, then it'll be back to 1275 after sleeving which means another Cooper 'S' Mk 1 block is 'as new' again. My 1973 Inno is now at 1330 and if/when it needs boring it'll be sleeved back to 1275.
However, if someone has a 1330 which has not been offset bored and wants it taken out to, say, 1380 that is their business. I'm just saying that geometrically it is possible to go bigger by offset boring a normally bored 1330. I am concerned that this desire to take road cars out to 1380 with no real performance gain will eventually cause a shortage of blocks. Different for real competition cars like Pauls as every 1 bhp is significant.
A 1330 is at +0.060, which is 0.030" on the radius. If the offset is 0.020" then so long as you are going to bore more than a further +0.020" it'll go OK and 1380 is more than +0.020" over a +0.060" overbore.

[Turbo Phil]

If you're looking for a performance increase purely from an overbore, then think again. You'll see little if any gain purely from an overbore, to get any benefit you'll need a decent cylinder head & cam fiited to.

[Cooperman]

If you're looking for a performance increase purely from an overbore, then think again. You'll see little if any gain purely from an overbore, to get any benefit you'll need a decent cylinder head & cam fiited to.

100% agree with this. I've seen 1380 engines which will never give of their best due to the heads not being good enough to flow the extra mixture required.
I measured the bhp of a 1275 which went to 1330 without any other mods to the existing spec and the gain was only 4 bhp.
For a 1380 to breathe it needs 37 mm inlet valves, 30.5 mm exhausts, a fully flowed head, a much better cam (at least a 276), a re-curved ignition system, good induction and carburation like twin 1.5" SU's, a Weber or similar flow-capable carb(s). All this plus a decent exhaust system - Maniflow of RC40 with a pipe diameter of 1.875" internal if you can get one that size, or 2" if not. To go to thast size without all the other mods is a waste of a good A-series block, apart from the additional costs of offset boring.

[Paul Wiginton]

Yes you can, why do you say you can't?

[Paul Wiginton]

Sure yours wasnt a linered block from the factory?

[Paul Wiginton]

No you can't. Different machine shops do and say different things and it also depends on the quality of their equipment

[L400RAS]

Nope, wouldn't use a linered block on a 1380, didn't think you could.

So you have a straight bored 1380? the wall between 2 & 3 must be wafer thin! I think someone told you a porky, as they didn't want to re-align the bores...